Apparatus operating on the displacement principle and usable both as a pump and as a motor

ABSTRACT

Apparatus operating on the displacement principle and usable both as a pump and as a motor, comprising a housing containing a number of displacement chambers having one or more plungers movable therein and coupled to a rotating shaft, said housing being provided with a first connection and with a second connection for a working medium, wherein the displacement chambers are each provided with a distribution system being coupled to control means which, at the beginning of each ingoing plunger stroke during which the displacement chamber decreases in volume and at the beginning of each outgoing plunger stroke during which the displacement chamber increases in volume, so adjust the distribution system under the influence of an impulse from the exterior that the distribution system connects the displacement chamber to one of the two connections selectively.

United States Patent 1191 Tulp June 26, 1973 [75] Inventor: Wfibrand Jan Tulp, Utrecht,

Netherlands [73] Assignee: N.V. Machinefahriek Stork-Jana,

Utrecht, Netherlands [22] Filed: Oct. 29, 1970 [21] Appl. No.: 85,114

' [30] Foreign Application Priority Data FOREIGN PATENTS OR APPLICATIONS 141,418 4/1935 ,Austria ..91/4so 9/1952 Great Britain 91/481 678,969 874,646 8/1961 Great Britain..... 672,240 5/1952 Great Britain 9l/47 C Primary Examiner-Paul E. Maslousky Attorney-Snyder and Butrum [5 7] ABSTRACT Apparatus operating on the displacement principle and usable both as a pump and as a motor, comprising a housing containing a number of displacement chambers having one or more plungers movable therein and coupled to a rotating shaft, said housing being provided with a first connection and with a second connection for aworking medium, wherein. the displacement chambers are each provided with a distribution system being coupled to control means which, at the beginning of each ingoing plunger stroke during which the displacement chamber decreases in volume and at the be ginning of each outgoing plunger stroke during which the displacement chamber increases in volume, so adjust the distribution system under the influence of an impulse from the exterior that the distribution system connects the displacement chamber to one of the two connections selectively.

14 Claims, 6 Drawing Figures sum 1 or 3 INVENTOR PATENIEBJIIII 26 975 FIG.

INVENTOR APPARATUS OPERATING ON THE DISPLACEMENT PRINCIPLE AND USABLE BOTH AS A PUMP AND AS A MOTOR This invention relates to an apparatus operating on the displacement principle and usable both as a pump and as a motor, comprising a housing containing a number of displacement chambers having one or more plungers movable therein and coupled to a rotating shaft, said housing being provided with a first connection and with a second connection for a working medium.

The object of this invention is to provide an apparatus of this type which can deliver and again receive both large and very small quantities of high-pressure working medium, the energy present in the medium being recovered. To this end, according to the invention, the displacement chambers are each provided with a distribution system for the working medium, said distribution system being coupled to control means which, at the beginning of each ingoing plunger stroke during which the displacement chamber decreases in volume and at the beginning of each outgoing plunger stroke during which the displacement chamber increases in volume, so adjust the distribution system under the influence of an impulse from the exterior that the distribution system connects the displacement chamber to one of the two connections selectively. Thus the various displacement chambers with plungers operate as a pump or'as a motor depending upon the setting of the distribution system. During one revolution of the shaft of the apparatus, therefore, a variable .number of plungers can be allowed to pump. I

According to the invention, the drive for an operating member of the distribution system may be so coupled to the drive for the plungers that when the associated plungers are at the beginning of their stroke the operating member is in the initial position from which said member has two possibilities of movement, i.e. a- .first possibility'for performing an operating stroke during which the distribution system connects the displacement chamber to the first connection and a second possibility for performing an operating stroke during which the distribution system connects the displacement chamber to'a second connection, at least one of said possibilities being blocked or released in the initial position of the operating member by the control means according to the pulse received by the latter. With such a construction there is a very rapid response to an impulse from the exterior to operate the distribution system, because no moving part has to be displaced. All that is required'is to block one possibility of movement of the operating member.

According to the invention, the distribution system may comprise an operating rod connected to a pivotable lever, the hinged end of which'is mounted on the armature of an electromagnet while the free end is driven by a system so coupled to the plunger drive that the lever is in themiddle position when the plungers are in the dead-center position and the lever has a second pivot axis between the point of application of the operating rod and the free driven end, said second pivot axis being pivotable together with the lever against spring action when the armature of the electromagnet is held .fast, and acting as a pivot axis when the armature can move freely, the arrangement being such that the ratio of the operative lever arms when the lever pivots about the pivot point on the electromagnet armature is the same or substantially the same as when the lever pivots about the spring-biassed axis. With such a construction of the apparatus the distribution system can react very rapidly. The distribution system is driven in synchronism with the pump plungers and when the plungers are in the dead-center position energization or nonenergization of the electromagnet determines the connection to be applied to the pump chambers. The magnet is not required to perform any movement in these conditions, so that the response time of the distribution system control is determined solely by the time required either to build up or not build up the magnetic field of the coil. The changeover can thus take place very rapidly, so that the apparatus can also be driven at high speed and the steps can be very small while the capacity of the apparatus as a whole is large enough. According to the invention, a simple manner of ensuring that the second pivot point is operative only when the electromagnet is not energized is for the spring-biassed pivot axis to be borne by a pivotable lever which is mounted in a fixed part of the housing and which is pressed against a fixed stop by a spring.

-In one advantageous embodiment of the apparatus according .to the invention, a numberof displacement chambers each having two plungers extend in the axial direction around a central driven shaft, the plungers moving towards and away from one another in each displacement chamber and being coupled to drive heads co-operating with two spaced swashplates disposed at an angle on theshaft, the displacement chambers each communicate with the central chamber of the associated distribution slide valve which, on a movement from the middle position to one side, connects the displacement chamber to a duct communicating with a connection for high-pressure and, on a movementv to the other side, connects the displacement chamber to a duct communicating with a connection for low pressure, the said slide valve being coupled to an operating rod extending axially in the housing, and the lever for driving the operating rod extends radially in the housing, and said lever can co-operate-- by its end extending towards the central shaft with an arm forming part of a swash-ring mounted for rotation about a bush which extends around the shaft and which is so' coupled to the shaft via a transmission that the bush rotates at twice the shaft speed. A construction of this kind is a simple way of ensuring synchronization between the operation of the pump plungers and operation of the distribution system.. 7

According to another feature of the invention, the main shaft of the apparatus may be provided with a plate having at least one hole which, by means of proximity switches, determines the time at which switching takes place under the influence of an electrical pulse from the exterior to either energize the electromagnet or not. With such a construction, the switching operation for energizing or not energizing the electromagnet automatically takes place just at the time when the distribution system is in the middle position. v

The arrangement described is very suitable more particularly for use as a pressure generator which can be used in a programmed control of hydraulic tools and,

more particularly, high-pressure presses. The operating under pressure or a small quantity of pressure medium can be withdrawn from said chamber. A step-wise control is thus obtained, in which the steps can be very small. The energy present in the pressure medium can re-deliver energy when pressure medium is withdrawn from the high-pressure chamber. This is very important when the pressure generator is used to operate a press. In the latter case, as a result of the compressibility of the oil a considerable amount of energy is stored up in the press owing to the elastic deformation of the press frame under the influence of the high pressures. It is a disadvantage if this large quantity of energy goes unused.

The invention will be explained in detail in the following description of one exemplified embodiment with reference to the drawing, wherein:

FIG. 1 is a longitudinal section of an apparatus according to the invention;

FIG. 2 is a cross-section onthe line IIII in FIG. 1;

FIG. 3 is a cross-section on the line III-III in FIG. 1;

FIG. 4 is a detail in cross-section on the line IV-IV in FIG. 2;

FIG. 5 is a detail in cross-section on the line V-V in FIG. 1;

FIG. 6 diagrammatically illustrates an exemplified embodiment of the apparatus according to the invention as a pressure generator for operating a press.

In the embodiment shown in FIG. 1 a rotatable shaft 2 is mounted in bearings 3 and 4 in a housing 1 constructed from various parts not indicated in detail. Inclined rotors 5 and 6 are mounted on the shaft and are spaced apart by a bush 7. Working chambers 8 are formed in the housing 1 and two plungers 9 and 10 can move towards and away from one another therein.

Each plunger is driven by a plunger rod 11 which at one end is coupled by aball and socket joint to the plunger 9 and at the other end to a shoe 12 bearing against the plate 5 by an adjustable, member 13. Referring to FIG.

2, the chamber 8 communicates via a passage 14 with ingly constructed duct 24 is provided on the right hand side of the chamber 15 and connects similarly with the annular duct 25 provided with a connecting orifice 26. When the valve 17 is moved to the left in FIG. 4, the

chamber 8 communicates with the widening 19 and hence with the duct 22 and the orifice 23. When the valve 17 is moved to the right, the chamber 8 communicates with the widening 24 and the orifice 26.

It will be apparent that when the shaft 2 rotates, the corotating plates 5 and 6 will cause the plungers 9 and 10 to move towards and away from one another. Depending upon the position of the slide valve 17, the chambers 8 then communicate with the orifice 23 or with the orifice 26.

As will be apparent from the right hand part of FIG. 1, the operating rod 18 for the slide valve 17 is mounted slidably in the housing 1. The end of the operating rod 18 is pivotally connected to a connecting rod 27 which is pivotally connected by a pivot 28 to a lever 29. The end of the lever 29 is pivotally connected by a pivot 30 to a forked member 31 integral with the armature 32 of an electromagnet 33 disposed in the housing 1. A terminal 34 is provided on the housing to supply energization current to the electromagnet 33 via a lead. A forked member 35 is mounted pivotally in the housing 1 at 36 and 37. A pivot 38 is also secured in the fork 35 and passes through the lever 29. The latter can rotate about this pivotwhen the electromagnet is not energized, as will be explained in detail hereinafter. A displaceable bush 39 is disposed in a bush 40 which is fixed in the housing 1. Inside the bushes 39 and 40 is a compression spring 41 which tends to press the bush 39 to the'right, during which it is supported by a ball 42 against the bottom end of the fork 35 which rests against a fixed supporting surface 43 of the housing 1. At the bottom end, lever 29 has a pin 44 passing through a pivot 45 mounted rotatably in a forked part 46 of a swashplate 47 which is mounted for rotation about a bush 49 by means of a bearing 48, said bush 49 being'rotatable about the shaft 2. The bush 49 is coupled to the shaft 2 via gearwheels 50, 51. and a gearwheel 52 rigidly secured to the shaft 2. The diameter of the gearwheels is such that the bush 49 rotates at twice the speed of the shaft 2.

A plate 53 formed with a number of holes 54 is mounted on the shaft 2 and its edge portion in which holes are formed rotates along a proximity switch 55 which reacts to the passage of a hole. The proximity switch 55 is connected by leads 56 to a relay 57 by means of which an energization current can be fed via leads 58 and the lead 59 to the terminal 34 and hence to the electromagnet 33. A change can be applied to the state of energization of the magnet 33 only when a 5 that when the plungers 9 and 10 are in the end posi-' tion the lever 29 is in a position such that the valve 17 is in the middle position. This position is shown by way of example in FIG. 4.

When the electromagnet 33 is energized, the armature 32 and hence the pivot 30 are held fast and when the swashplate 47 rotates the lever will pivot about the pivot 30 so that, for example, the rod 27 and hence the operating rod 18 for the valve 17 are moved to the left. The fork 35 also pivots to the left about the pivots 36 and 37 via the pivot 38, the bush 39 being moved to the left against the action of the spring 41.

When, on the other hand, the electromagnet is not energized, the fork 35 is pressed against the surface 43 by the spring 41 and the pivot 38 acts as a pivot axis for the lever 29. On rotation of the plate 47, the rod 27 and hence the operating rod 18 will now be moved to the right. Whether or not the electromagnet 33 is energized at the beginning of the stroke of the lever 29 governs which of the orifices 23 or 26 is connected with the working chamber 8 of the pump plungers 9 and 10. This state is thus determined when the plungers 9 and 10 are in the dead-center position and the plate 47 is in the position shown in FIG. 1.

Consequently, virutally no time is required for the adjustment of the state of movement of the lever 29. This time is determined by the time required to build up and break off the magnetic field of the coil 33.

As will be seen from FIG. 2, the housing 1 contains five sets of plungers 9 and 10. All these plungers are correspondingly provided with a slide valve 17 and an associated operating mechanism for the same.

Since it is possible to determine whether the working chamber 8 is to be connected to the orifice 23 or 26 at the beginning of each ingoing and outgoing stroke of the plungers 9 and 10, it is possible very accurately to determine the amount of pressure medium to be fed to or withdrawn from a given chamber. Although the control process is not continuous, the steps are very small since they are determined by a swept volume of just one working chamber 8. During one revolution of the shaft 2, some of the chambers 8 can operate as pump chambers while others act as motor chambers.

Since the plungers 9 and 10 and the associated rods 11 and shoes 12 are provided with ducts, continuous lubrication of the moving parts is guaranteed. The shoes 12, 13 are pressed against the plates 5 and 6 by springs. This is important when the apparatus is started if the chambers 8 are'still unpressurized.

In the embodiment illustrated in FIG. 6, an apparatus according to the invention is used as a pressure generator in combination with a press which is illustrated diagrammatically. The press is formed by cylinder 60 with a plunger 61 movable therein. The space above the plungers is connected to an oil reservoir 63 via an opening closed by a valve 62.

The control plunger 64 and the associated return spring are so dimensioned that the pre-fllling valve 62 is opened when the pressure in the space above the plunger 64 is greater than in the cylinder chamber 65. The space above the plunger 64 communicates via a conduit 66 with a conduit 67 which connects the reservoir 63 to a conduit 67' which communicates, on the one hand, with the cylinder 60, namely the annular chamber 68 at the underside of the thickest portion of the plunger 61, and on the other hand with one of the connection orifices of a pressure generator 69 according to the invention. The other orifice of the pressure generator 69 is connected via aconduit 70 to the chamber 65 above the plunger 61. A hydraulically operated valve 72 is provided in the conduit 67 between the connection of the conduit 66 and the reservoir 63. The valve 72 is operated by the pressure in conduit 70 via conduit 73.

The pressure in the conduits 67 and 66 is produced by the force exertedby the annular part of the plunger 61 on the oil in the chamber 68. This force is produced by the weight of the plunger 61 and of the ram 75, and by the force exerted by the oil in the chamber 65 on the plunger 61. The pressure in the chamber 65- is produced by the pressure of the oil in the reservoir 63.

Whenever the ram 75 experiences no force in the upward direction, the pressure in the chamber 68 and hence in the conduits 67 and 66 would cease, and the pre-fill valve 62 is open and the oil can flow without obstruction from the reservoir 63'to the cylinder chamber 65'and vice versa.

On an upward stroke of the ram, the speed of the plunger 61 is determined by the amount of oil delivered by the pressure generator 69 which is driven by the electric motor 74 into the chamber 68 via the conduit 67. On a downward stroke of the plunger 61, the speed is determined by the amount received by the pressure generator 69 from the chamber 68 via the conduit 67'. In this latter case, the pressure generator 69 thus acts as a motor.

The oilfed to or withdrawn from the chamber 68 by the pressure generator 69 is drawn from or fed to the chamber 65 via the conduit 70.

When the ram 75 encounters resistance, the pressure in the chamber 68 and in the conduits 67 and 66 ceases and the pre-filling valve 62 closes. During the subsequent press stroke, the speed of the plunger 61 is determined by the amount of oil delivered to the cylinder chamber 65 by the pressure generator 69 via the conduit 70. An equal amount of oil is then fed from the reservoir 63 via the conduit 67' and via the valve 72, which is now open since there is high pressure in the conduits and 73.

On completion of the press stroke, there is a quantity of highly compressed oil in the cylinder chamber 65. To eliminate the pressure above the plunger 61, a quantity of oil must be discharged to the pressure generator via the conduit 70. The pressure generator new acts as a motor. An equal quantity of oil is discharged via the conduits 67 and 67 to the reservoir 63 via the valve 72, which remains open until the pressure above the plunger 61 has been reduced to the pressure in the reservoir 63.,When this condition occurs, the valve 72 closes and the valve 62 opens, whereupon the plunger can move upwards.

The position of the plunger 61 and the ram is determined by a pick-up 76. The information from the pick-up 76 is transmitted to a controller 77 which also receives from a programmer 78 the required information on the position that the plunger 61 and the ram 75 are required to assume. The controller 77 transmits the required pulses to the pressure generator 69.

What I claim is:

1. Apparatus operating on the displacement principle, comprising in combination:

a housing having a plurality of chambers, each having at least one plunger reciprocable therein, and said housing having a pair of ports for working fluid; shaft means for reciprocating each plunger from a first extreme position to a second extreme position and back to said first extreme position;

fluid distribution means for controlling fluid flow between each chamber and said ports;

actuating means for moving each fluid distribution means from a blocking position in which both said ports are blocked with respect to the associated chamber when the associated plunger is in either of its extreme positions to a selected one of a first operative position in which the associated chamber is communicated with one port and a second operative position in which the associated chamber is communicated with the other port as the associated plunger is moving between its extreme positions; and

means for conditioning said actuating means to move the fluid distribution means to a selected one of its first and second operative positions when the associated plunger is at either of its extreme positions.

2. Apparatus according to claim 1 wherein each said fluid distribution means comprises a reciprocable spool valve.

3. Apparatus according to claim 2 wherein each said actuating means comprises a first lever connected between its ends to an associated spool valve, means for oscillating one end of said first lever, a second lever pivoted at one end to said housing and to said first lever in spaced relation thereto, and resilient means for resiliently urging said second lever to a predetermined position, said means for conditioning being effective selectively to pivotally anchor and to release the opposite end of said first lever.

4. Apparatus according to claim 3 wherein said means for conditioning comprises an armature pivotally connected to said opposite end of the first lever and a winding associated with said armature.

5. Apparatus according to claim 4 wherein said means for oscillating said one end of first lever comprises a member geared 2:1 to said shaft means so as to oscillate said first lever at twice the rate of said plungers.

6. Apparatus according to claim 5 wherein said means for conditioning includes a timing disc driven by said shaft means and switch means associated with said timing disc for changing the state of energization of said winding only when an associated plunger is at one of its extreme positions.

7. Apparatus according to claim 6 wherein a pair of opposed plungers are disposed in each chamber and wherein said shaft means includes a pair of swashplates for actuating said pairs of plungers.

8. Apparatus according to claim 7 wherein said member of said means for oscillating comprises a swashplate.

9. ln a fluid displacement device including a housing presenting a plurality of chambers and having at least one plunger in each chamber, said housing having a pair of ports for working fluid, valve means associated with each chamber for selectively connecting each chamber to one of said ports, and shaft means associated with said plungers for rotation in unison with reciprocation of said plungers, the improvement which comprises:

actuating means for moving each said valve means to a selected one of its connecting conditions during movement of the associated plunger; and

control means for establishing the subsequent connecting condition of each said valve means as effected by said actuating means only when the associated plunger is at the ends of its stroke.

10. In a fluid displacement device as defined in claim 9 wherein said control means comprises an electromagnet device including a movable armature and said actuating means comprises a lever system controlled by the position of said armature.

11. A fluid displacement device comprising, in combination:

a housing presenting a plurality of chambers and having at least one reciprocable plunger in each chamber, said housing having a pair of working fluid ports; valve means associated with each chamber for controlling flow of fluid between said ports, said valve means having a blocking position blocking both said ports from an associated chamber, a first operative position connecting one port to the associated chamber and a second operative position connecting the other port to said associated chamber;

shaft means associated with said plungers for rotation in unison with reciprocation of said plungers;

actuating means for moving each said valve means from blocking position to one of its operative positions and back to blocking position during each unidirectional movement of an associated plunger;

means for conditioning said actuating means while said valve means is in blocking position to move said valve means to a selected one of said operative positions during the next following unidirectional movement of the associated plunger whereby the direction of fluid flow between said ports through the associated chamber may be controlled at will.

12. A fluid displacement device as defined in claim 11 wherein said actuating means comprises an oscillating lever system and said means for conditioning establishes the axis of oscillation of said lever system.

13. A fluid displacement device as defined in claim 14 wherein said means for conditioning comprises an armature connected to said lever system and an elec tromagnetic winding means for selectively holding an releasing said armature.

14. A fluid displacement device as defined in claim 14 including means for individually controlling said means for conditioning whereby fluid flow between said ports through individual chambers may be in relatively reverse directions.

t t t t 

1. Apparatus operating on the displacement principle, comprising in combination: a housing having a plurality of chambers, each having at least one plunger reciprocable therein, and said housing having a pair of ports for working fluid; shaft means for reciprocating each plunger from a first extreme position to a second extreme position and back to said first extreme position; fluid distribution means for controlling fluid flow between each chamber and said ports; actuating means for moving each fluid distribution means from a blocking position in which both said ports are blocked with respect to the associated chamber when the associated plunger is in either of its extreme positions to a selected one of a first operative position in which the associated chamber is communicated with one port and a second operative position in which the associated chamber is communicated with the other port as the associated plunger is moving between its extreme positions; and means for conditioning said actuating means to move the fluid distribution means to a selected one of its first and second operative positions when the associated plunger is at either of its extreme positions.
 2. Apparatus according to claim 1 wherein each said fluid distribution means comprises a reciprocable spool valve.
 3. Apparatus according to claim 2 wherein each said actuating means comprises a first lever connected between its ends to an associated spool valve, means for oscillating one end of said first lever, a second lever pivoted at one end to said housing and to said first lever in spaced relation thereto, and resilient means for resiliently urging said second lever to a predetermined position, said means for conditioning being effective selectively to pivotally anchor and to release the opposite end of said first lever.
 4. Apparatus according to claim 3 wherein said means for conditioning comprises an armature pivotally connected to said opposite end of the first lever and a winding associated with said armature.
 5. Apparatus according to claim 4 wherein said means for oscillating said one end of first lever comprises a member geared 2:1 to said shaft means so as to oscillate said first lever at twice the rate of said plungers.
 6. Apparatus according to claim 5 wherein said means for conditioning includes a timing disc driven by said shaft means and switch means associated with said timing disc for changing the state of energization of said winding only when an associated plunger is at one of its extreme positions.
 7. Apparatus according to claim 6 wherein a pair of opposed plungers are disposed in each chamber and wherein said shaft means includes a pair of swashplates for actuating said pairs of plungers.
 8. Apparatus according to claim 7 wherein said member of said means for oscillating comprises a swashplate.
 9. In a fluid displacement device including a housing presenting a plurality of chambers and having at least one plunger in each chamber, said housing having a pair of ports for working fluid, valve means associated with each chamber for selectively connecting each chamber to one of said ports, and shaft means associated with said plungers for rotation in unison with reciprocation of said plungers, the improvement which comprises: actuating means for moving each said valve means To a selected one of its connecting conditions during movement of the associated plunger; and control means for establishing the subsequent connecting condition of each said valve means as effected by said actuating means only when the associated plunger is at the ends of its stroke.
 10. In a fluid displacement device as defined in claim 9 wherein said control means comprises an electromagnet device including a movable armature and said actuating means comprises a lever system controlled by the position of said armature.
 11. A fluid displacement device comprising, in combination: a housing presenting a plurality of chambers and having at least one reciprocable plunger in each chamber, said housing having a pair of working fluid ports; valve means associated with each chamber for controlling flow of fluid between said ports, said valve means having a blocking position blocking both said ports from an associated chamber, a first operative position connecting one port to the associated chamber and a second operative position connecting the other port to said associated chamber; shaft means associated with said plungers for rotation in unison with reciprocation of said plungers; actuating means for moving each said valve means from blocking position to one of its operative positions and back to blocking position during each unidirectional movement of an associated plunger; an means for conditioning said actuating means while said valve means is in blocking position to move said valve means to a selected one of said operative positions during the next following unidirectional movement of the associated plunger whereby the direction of fluid flow between said ports through the associated chamber may be controlled at will.
 12. A fluid displacement device as defined in claim 11 wherein said actuating means comprises an oscillating lever system and said means for conditioning establishes the axis of oscillation of said lever system.
 13. A fluid displacement device as defined in claim 14 wherein said means for conditioning comprises an armature connected to said lever system and an electromagnetic winding means for selectively holding and releasing said armature.
 14. A fluid displacement device as defined in claim 14 including means for individually controlling said means for conditioning whereby fluid flow between said ports through individual chambers may be in relatively reverse directions. 